Various fans are used for electronic devices for the purpose of providing blast or internal cooling, for example. Among these fans, a cross-flow fan that is cylindrical, long, and thin provides an effect of being capable of providing a large air pressure for a certain blade diameter, and therefore, is widely used for air conditioners, image forming apparatuses, and the like. A cross-flow fan tends to generate a large wind noise when the volume of blast increases. Therefore, various types of cross-flow fans need to be produced according to usage or specification of electronic products.
For example, a technology of configuring a long and thin cross-flow fan by connecting a plurality of relatively short impellers in the direction of a rotation axis has been known as a related technology (see Patent Literature 1, for example).